This application claims priority to an application entitled xe2x80x9cWAVELENGTH CONVERTER AND OPTICAL CROSS-CONNECT SYSTEM USING THE SAME,xe2x80x9d filed in the Korean Intellectual Property Office on Nov. 22, 2002 and assigned Ser. No. 2002-73163, the contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a wavelength converter and an optical cross-connect system using the same and more particularly to an optical cross-connect system for enabling each wavelength converter to receive a necessary light source from a multi-wavelength light source.
2. Description of the Related Art
Following the current trend of a rapid development of wavelength division multiplexing (WDM) techniques which provides several wavelengths within one optical fiber, it is now possible to transmit a plurality of storage data in large quantity using a single optical fiber in a very high-speed optical communication field. In the near future, it is anticipated that current linear or circular networks utilized for transmitting data via a fixed path of an optical communication network will be changed to xe2x80x9cAll Optical Transmission Networksxe2x80x9d (AOTNs), which provides a means for dynamically reconstructing its own network configurations by diverting an optical path when necessary. Particularly, it is anticipated that a backbone network will be replaced with a mesh-type network based on Optical Cross-Connector (OXC) to provide reconstructions of circuit lines at each node.
Note that the optical cross-connector (OXC) can be implemented with an electric method or an optical method. The electric method converts an input optical signal into an electric signal using optic-to-electric conversion and performs a switching operation, then reconverts the electric signal back into an optical signal. In contrast, the optical method de-multiplexes a wavelength-multiplexed optical signal received from an input link and switches the signal in wavelength units using a space switch. This type of an optical method is further classified into several sub-methods according to a wavelength converter (WC). For example, one such sub-method is a wavelength interchanging cross-connector, known for ensuring the extensiveness of a routing algorithm as well as lowering the probability of a channel blocking by a wavelength converter.
FIG. 1 is a view illustrating a block diagram of a conventional wavelength interchanging cross-connector. As shown, the conventional cross-connector includes a wavelength division demultiplexer 10, an optical space switch 20, a plurality of wavelength converters 30xcx9c33, a wavelength division multiplexer 40, and a plurality of wavelength light sources 50xcx9c53. In FIG. 1, a reference character ADD denotes the added signal channel, and the other reference character DROP denotes the dropped signal channels.
In operation, an incoming optical signal received via an input optical fiber is wavelength demultiplexed by the wavelength-division-demultiplexer 10, then cross-connected by the optical space switch 20. The cross-connected optical signal is wavelength-converted by the wavelength converters 30xcx9c33, then applied to and multiplexed by the wavelength-division-multiplexer 40, thus generating a multiplexed optical signal on an output optical fiber. The optical cross-connector has a plurality of input links such that the number of optical signal channels having the same wavelengths is the same as the number of links. However, if at least two each wavelengths arc routed to one common output link, a line contention occurs. To solve this problem, if a wavelength conversion towards an unused wavelength is provided at a link to be outputted, the network availability increases. Therefore, a wavelength converter is mounted to each channel of the wavelength division multiplexer 40 to increase the network availability.
However, the aforementioned conventional wavelength interchanging cross-connector enables each of the wavelength converters 30xcx9c33 to receive a light source corresponding to a wavelength of the wavelength division multiplexer 40 using a plurality of individual light sources 50xcx9c53. Therefore, the system further requires a light source stabilizer. Moreover, as the conventional wavelength interchanging cross-connector mounts a number of light sources for different wavelengths, the system requires a number of wavelength converter models.
Accordingly, there is a need to provide an improved cross-connect system so that additional components required to achieve the conversion of wavelengths can be minimized.
One aspect of the present invention is to provide a wavelength converter and an optical cross-connect system using the same for enabling one multi-wavelength light source to provide each wavelength converter with the necessary tuned wavelength, without using individual light sources with different wavelengths for each wavelength of a multiplexer as in the prior art system.
Another aspect of the present invention is to provide a wavelength converter using a multi-wavelength light source which includes: a wavelength division multiplexer for dividing input optical signals into wavelength units or collecting the divided wavelength-unit optical signals; a wavelength converter for performing a wavelength conversion on an input multi-channel optical signal; a multi-wavelength light source for generating a multi-wavelength optical signal needed to perform the wavelength conversion of the wavelength converter; a first optical circulator for transmitting the multi-wavelength optical signal to the wavelength division multiplexer and for outputting a transmission optical signal generated from the wavelength division multiplexer to an output link; and, a second optical circulator for providing a single-wavelength light source demultiplexed by the wavelength division multiplexer as a tuned wavelength needed to perform the wavelength conversion of the wavelength converter and for outputting a wavelength-converted transmission optical signal generated from the wavelength converter to the wavelength division multiplexer.
Yet another aspect is to provide a wavelength interchanging cross-connector, which includes: first and second wavelength division multiplexers for dividing input optical signals for all directions into wavelength units, or collecting the divided wavelength-unit optical signals; a space switch for switching input signals with different wavelengths via the first wavelength division multiplexer; a wavelength converter for performing a wavelength conversion on the switched signals to be converted into signals corresponding to each wavelength of the second wavelength division multiplexer; a multi-wavelength light source for generating a multi-wavelength optical signal needed to perform the wavelength conversion of the wavelength converter; a first optical circulator for transmitting the multi-wavelength optical signal to the second wavelength division multiplexer and for outputting a transmission optical signal generated from the second wavelength division multiplexer to an output link; and, a second optical circulator for providing the multi-wavelength optical signal demultiplexed by the second wavelength division multiplexer as a tuned wavelength needed to perform the wavelength conversion of the wavelength converter and for outputting a wavelength-converted transmission optical signal generated from the wavelength converter to the wavelength division multiplexer.
Yet another aspect is that the present invention may be realized in a simple, reliable, and inexpensive implementation.